Optical detection device, optical detection method, method for designing optical detection device, sample classification method, and defect detection method

Abstract

An optical detection device is an optical detection device that detects a desired wavelength component included in input light, and includes: a spectrometer including, for instance, a diffraction grating that receives the input light as an input and outputs an alignment of spectra each of which is a duplication of a spectrum of the input light; a second slit array including an array of three or more slits that pass light beams of wavelengths at three or more locations in the alignment of the spectra that are output from the spectrometer; and an imaging element composed of an array of pixels that receive the light beams, having passed through the second slit array, each of the light beams having three or more wavelength components. At least two pitches between slits are different in the array of the three or more slits included in the second slit array.

The invention claimed is: 
     
       1. An optical detection device that detects a desired wavelength component included in input light, the optical detection device comprising:
 a spectrometer that receives the input light as an input and outputs, at a first pitch, an alignment of spectra each of which is a duplication of a spectrum of the input light; 
 a slit array including an array of three or more slits that pass light beams of wavelengths at three or more locations in the alignment of the spectra that are output from the spectrometer; and 
 an imaging element composed of an array of pixels that receive the light beams having passed through the slit array, each of the light beams having three or more wavelength components separated by a fixed wavelength range so that the three or more wavelength components are shifted from each other in a fixed wavelength cycle, wherein 
 at least two pitches between slits are different in the array of the three or more slits, and 
 a second pitch that is one of the at least two pitches is different from the first pitch. 
 
     
     
       2. The optical detection device according to  claim 1 , wherein
 in the alignment of the spectra, parts of adjacent spectra spatially overlap each other, and 
 at least one of the three or more slits passes a light beam having wavelength components corresponding to a same spatial location in spectra having parts spatially overlapping each other in the alignment of the spectra. 
 
     
     
       3. The optical detection device according to  claim 1 , wherein
 each of the spectra includes a first peak and a second peak, and 
 the three or more slits include a slit that passes a light beam of a wavelength corresponding to the first peak and a slit that passes a light beam of a wavelength corresponding to the second peak. 
 
     
     
       4. The optical detection device according to  claim 3 , wherein
 the array of pixels receives light in a desired wavelength range, and 
 the first peak and the second peak are separated by a wavelength range greater than a wavelength range equivalent to the first pitch. 
 
     
     
       5. A sample classification method for classifying a type of a sample, the sample classification method comprising:
 obtaining a spectrum for each of samples and determining, through compressed sensing performed on spectra obtained, three or more measurement wavelengths to be used for reconstructing the spectrum, the spectrum being a transmission spectrum or an absorption spectrum; 
 (i) measuring, for each of samples whose types are known, wavelength components of the three or more measurement wavelengths, using the optical detection device according to  claim 1 , and (ii) generating reference data in which a measurement result obtained by measuring the samples whose types are known is associated with a corresponding one of the types; and 
 (i) measuring, for a sample whose type is unknown, wavelength components of the three or more measurement wavelengths, using the optical detection device, and (ii) determining a type of the sample by performing matching between a measurement result obtained by measuring the sample whose type is unknown and the reference data. 
 
     
     
       6. A defect detection method for detecting a defective sample, the defect detection method comprising:
 obtaining a spectrum for each of samples and determining, through compressed sensing performed on spectra obtained, three or more measurement wavelengths to be used for reconstructing the spectrum, the spectrum being a transmission spectrum or an absorption spectrum; 
 (i) measuring, for each of samples that are good products, wavelength components of the three or more measurement wavelengths, using the optical detection device according to  claim 1 , and (ii) generating reference data indicating a measurement result obtained by measuring the samples that are good products; and 
 (i) measuring, for a sample that whether the sample is a good product or a defective product is unknown, wavelength components of the three or more measurement wavelengths, using the optical detection device, and (ii) determining whether the sample is a good product or a defective product by performing matching between a measurement result obtained by measuring the sample that whether the sample is a good product or a defective product is unknown and the reference data. 
 
     
     
       7. An optical detection method for detecting a desired wavelength component included in input light, the optical detection method comprising:
 upon receiving the input light as an input, outputting, at a first pitch, an alignment of spectra, each of which is a duplication of a spectrum of the input light; 
 passing, by a slit array including an array of three or more slits, light beams of wavelengths at three or more locations in the alignment of the spectra that are output; and 
 detecting, by an imaging element composed of an array of pixels, the light beams that have passed through the slit array, each of the light beams having three or more wavelength components separated by a fixed wavelength range so that the three or more wavelength components are shifted from each other in a fixed wavelength cycle, wherein 
 at least two pitches between slits are different in the array of the three or more slits, and 
 a second pitch that is one of the at least two pitches is different from the first pitch. 
 
     
     
       8. A method for designing an optical detection device that detects a desired wavelength component included in input light, the optical detection device including:
 a spectrometer that receives the input light as an input and outputs, at a first pitch, an alignment of spectra each of which is a duplication of a spectrum of the input light; 
 a slit array including an array of three or more slits that pass light beams of wavelengths at three or more locations in the alignment of the spectra that are output from the spectrometer; and 
 an imaging element composed of an array of pixels that receive the light beams having passed through the slit array, each of the light beams having three or more wavelength components separated by a fixed wavelength range so that the three or more wavelength components are shifted from each other in a fixed wavelength cycle, wherein 
 at least two pitches between slits are different in the array of the three or more slits, and 
 a second pitch that is one of the at least two pitches is different from the first pitch, 
 the method comprising: 
 determining positions of the three or more slits in the slit array so that the three or more slits include a slit that passes a light beam of a wavelength corresponding to a location that is characteristic to the spectrum of the input light; and 
 fabricating the optical detection device in accordance with a final design obtained by performing the method. 
 
     
     
       9. The method according to  claim 8 , wherein
 each of the spectra includes a first peak and a second peak, and 
 in the determining of the positions, the positions of the three or more slits in the slit array are determined so that the three or more slits include a slit that passes a light beam of a wavelength corresponding to the first peak and a slit that passes a light beam of a wavelength corresponding to the second peak. 
 
     
     
       10. The method according to  claim 8 , further comprising:
 prior to the determining of the positions, obtaining the spectra of the input light, and determining, through compressed sensing performed on the spectra obtained, three or more measurement wavelengths to be used for reconstructing each of the spectra, wherein 
 in the determining of the positions, the positions of the three or more slits in the slit array are determined so that the three or more slits include slits each of which passes a light beam of a different one of the three or more measurement wavelengths determined in the determining of the three or more measurement wavelengths. 
 
     
     
       11. The method according to  claim 10 , wherein
 in the determining of the three or more measurement wavelengths, the three or more measurement wavelengths in each of the spectra are determined by applying a sparse principal component analysis to the spectra obtained.